1. Field of the Invention
The present general inventive concept relates to a scanning unit, a manufacturing method thereof and an image forming apparatus, and more particularly, to a scanning unit which minimizes vibration while reciprocating in a linear direction, a manufacturing method thereof and an image forming apparatus.
2. Description of the Related Art
A conventional scanning unit scans an image of documents. The scanning unit emits light to a predetermined position through a lighting module, and forms an image with the light reflected by the documents on an image sensor through an imaging lens, thereby scanning the image information formed in the predetermined position of the documents.
The scanning unit may be employed in an image forming apparatus to store the scanned image information as a file or to copy the scanned image information to a print medium. The image forming apparatus may include a multi-function device, a photocopier, a scanner, etc.
As illustrated in FIG. 1, a scanning unit may reciprocate in a main scanning direction X to scan an overall page of the document provided in a plate. The image forming apparatus includes a guide shaft which has a lengthwise direction as the main scanning direction to reciprocate the scanning unit. Two shaft insertion members are installed in the scanning unit to insert the guide shaft thereinto and move along the guide shaft.
If a gap between an external diameter of the guide shaft and an internal diameter of the shaft insertion members is increased, the scanning unit is vibrated, thereby lowering a quality of the scanned image information. A component tolerance (i.e., an allowable deviation from a predetermined standard) is strictly managed to prevent the quality of the image from being lowered and to minimize the gap therebetween.
However, even if the component tolerance is strictly managed, the two shaft insertion members may be easily distorted when installed. Thus, coaxial tolerance, i.e. alignment tolerance may occur. While the component tolerance is several micrometers, the alignment tolerance is generally 30 μm to 40 μm. Thus, the lowered image quality is mainly resulted from the alignment tolerance.
The alignment tolerance should be minimized if the two shaft insertion members are installed.